Various attempts have been made to lock swinging doors in place. U.S. Pat. No. 1,723,007 of Bittorf describes a security device wherein a sliding locking bolt is prevented from being pried upwardly from the outside by a restricting notch in double cam piece. The sliding bolt and bracket is attached to the door itself, thus increasing the weight of the door.
Moreover, U.S. Pat. No. 1,302,409 of Murphy describes a door security device which is also secured to the face of a door, thus adding unnecessary weight to the door. In Murphy '409, a sliding bolt moves down to lock in place within a groove within the floor adjacent to the door.
Both the Bittorf '007 and Murphy '409 patents have the disadvantages of increasing the weight upon the door, thus interfering with the ease of swinging the door open and closed. In addition, the attached bolt and brackets constitute protrusions, which may strike a user's leg during the process of opening and closing the door.